This paper presents Computational Fluid Dynamics (CFD) investigations of a single-phase rectangular natural circulation loop, aimed to single out the physical phenomena which trigger the thermal behaviour of a natural circulation loop. CFD simulations - performed adopting ANSYS CFX 11.0 software - showed that prediction of buoyancy driven flows requires very accurate boundary conditions. In fact, several transient simulations where performed using boundary conditions of increasing complexity, starting from simulating the fluid domain only, and then adding the solid components of the loop (e.g. the materials and thickness of the pipes). Satisfactory results were obtained only with complex grids and conjugated heat transfer simulations. The simulations also gave information about the flow reversal mechanism which was impossible to notice from the experimental data. It was also noticed that the flow inside the loop is characterized by important 3D effects. CFX results concerning an unstable test were also compared with Fluent 6.3 simulations performed at the University of Genoa.
Analysis of Natural Circulation Experimental Data by Means of CFD Codes
D'AURIA, FRANCESCO SAVERIO
2009-01-01
Abstract
This paper presents Computational Fluid Dynamics (CFD) investigations of a single-phase rectangular natural circulation loop, aimed to single out the physical phenomena which trigger the thermal behaviour of a natural circulation loop. CFD simulations - performed adopting ANSYS CFX 11.0 software - showed that prediction of buoyancy driven flows requires very accurate boundary conditions. In fact, several transient simulations where performed using boundary conditions of increasing complexity, starting from simulating the fluid domain only, and then adding the solid components of the loop (e.g. the materials and thickness of the pipes). Satisfactory results were obtained only with complex grids and conjugated heat transfer simulations. The simulations also gave information about the flow reversal mechanism which was impossible to notice from the experimental data. It was also noticed that the flow inside the loop is characterized by important 3D effects. CFX results concerning an unstable test were also compared with Fluent 6.3 simulations performed at the University of Genoa.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
